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Saturday, July 21, 2012

Contrary to what this blog might make you think, I actually don’t communicate every thought I have. A lot of what happens between my ears stays there, mostly out of fear that if I ask the “Does anyone else ever notice this?” questions, the response I’ll get will be, “No, that’s only you because your brain is broken.”

However, I’ll occasionally learn that these between-my-ears things happen to everyone. It’s validating. Until I was about six or seven, I assumed I was the only one who could close his eyes and see pulsating blobs of light that eventually transformed into recognizable shapes. Then a friend mentioned them. Me, my little mind blown: “You see them too?” Or that sensation of tripping that you get immediately before you fall asleep? I’d never discussed it with anyone until I learned in a high school psychology class that the hypnic jerk happens to everyone. (Great band name, BTW: The Hypnic Jerks.) And on this very blog, I got to write about my realizations that phonesthemes and logophobia were actual things and not just weird ideas that only I entertained.

Last week, I learned about another one, thanks to a link from Dina. It’s my word of the week.

chronostasis (KRO-no-stay-sis) — noun: the “stopped-clock illusion,” or the perception that the first visual impression following a quick eye movement appears to be extended in time.

Have you ever darted your eyes at a clock and thought the second hand was taking an especially long time to click over to the next position? But after that it began clicking forward in even intervals as it’s supposed to? You’re not alone. That’s chronostasis — literally “standing time.” And while Wikipedia points out that it occurs every time we perform a saccade — another five-dollar word, it means “quick eye movement” and comes from the French word meaning “jerk” — it’s just easier to observe chronostasis when we’re looking at a timepiece or something else that makes regular, uniform changes.

Chronostasis need not even be visual, according to the 2002 Oxford study “Auditory chronostasis: Hanging on the telephone,” which had subjects estimate the elapsed time between tones heard on headphones. According to Wikipedia (and, I’ll bet, that study as well, were I able to read more than the abstract), auditory chronostasis occurs when you dial a phone number, raise the handset to your ear and and perceive the time between rings.

So what gives? According to a 2001 study, it’s a side-effect of our brains’ desire for continuity in spite of those quick eye movements. The neuroscience blog The MacGuffin explains more:

When our eyes move, the image reflected on to the retina is also in motion. This creates motion blur… . A blurred image being utterly incomprehensible (and of no use) to us sighted humans, our brains have a mechanism to circumvent the blur and create a comprehensible image. This phenomenon is known as saccadic masking. During saccadic masking, the blur is suppressed, along with visual processing, and the gap in visual processing that should be experienced as your eyes move from on side to another. The brain then replaces the blur with an image of the very next thing that your eyes fixate on.

And also this:

If the brain is replacing a past image with a current image, does that mean what I’m seeing is not really in the present but the past? Yes, in fact, human awareness or what we experience as the “present” is actually the very recent past; more specifically our consciousness lags 80 milliseconds behind actual events. This is how saccadic masking and chronostasis are possible; before we become aware, our brain has to make sense of stimuli first, which takes just about 80 milliseconds.